Bathtub pillow



FIG. 1 is a front elevated view of a bathtub pillow showing my new design;

FIG. 2 is a rear elevated view of the bathtub pillow;

FIG. 3 is a side elevated view of the bathtub pillow;

FIG. 4 is a top plan view of the bathtub pillow; and,

FIG. 5 is a bottom plan view of the bathtub pillow. 

The ornamental design for a bathtub pillow, as shown and described. 